Onopordum

Onopordum, or cottonthistle, is a genus of plants in the tribe Cardueae within the family Asteraceae. They are native to southern Europe, northern Africa, the Canary Islands, the Caucasus, and southwest and central Asia. They grow on disturbed land, roadsides, arable land and pastures.
They are biennials (rarely short-lived perennials) with branched, spinose winged stems, growing 0.5–3 m tall. In the first season they form a basal rosette of gray-green felted leaves and rarely a few flower heads. In the second season they grow rapidly to their final height, flowering extensively, and then die off after seed maturation.
The leaves are dentate or shallowly lobed to compound with several pinnatifid or deeply cut leaflets, and strongly spiny. The terminal flower head is typical for thistles, a semi-spherical to ovoid capitulum with purple (seldom white or pink) disc florets. There are no ray florets. The receptacle is glabrous with dentate margins. The tube of the corolla is slender, sac-shaped and symmetrical. The anthers have awl-shaped outgrowths on the top. The capitula have several overlapping rows of leathery basal simple linear-lanceolate spines. These are smooth to slightly pubescent.
These plants propagate only by seed. The seed heads mature in mid-summer, releasing their seeds. The fruit is a glabrous achene, 4–6 mm long and with 4-50 ribs. The pappus consists of many rows of simple, fine to minutely rough hairs, united in a circular base.
Onopordum species are used as food plants by the larvae of some Lepidoptera species including Coleophora onopordiella (feeds exclusively on O. acanthium).
In the Greek island of Crete a native species called agriagginara (αγριαγγινάρα) or koufoti (κουφωτοί) has its heads (flowers) and tender leaves eaten raw by the locals.
Species
Onopordum acanthium L. - Cotton thistle, Scotch thistle, Scotch common-thistle, heraldic thistle, woolly thistle - widespread across Europe and temperate Asia
Onopordum acaulon L. - Stemless thistle, horse thistle - France, Spain, Algeria, Morocco, Tunisia
Onopordum alexandrinum Boiss. - Egypt, Palestine, Lebanon, Syria, Israel, Jordan
Onopordum algeriense (Munby) Pomel - Algeria
Onopordum ambiguum Fresen. - Egypt, Palestine, Lebanon, Syria, Israel, Jordan
Onopordum anatolicum (Boiss.) Eig. - Turkey
Onopordum arenarium M.Hossain & M.A.A.Al-Sarraf - Algeria, Morocco, Tunisia, Libya
Onopordum armenum Grossh. - Caucasus, Iran, Turkey
Onopordum blancheanum (Eig) Danin - Israel, Palestine, Jordan, Syria, Lebanon
Onopordum boissierianum Raab-Straube & Greuter - Turkey
Onopordum bracteatum Boiss. & Heldr. - Greece, Turkey, Cyprus
Onopordum canum Eig - Iran, Jordan, Israel, Turkey
Onopordum carduchorum Bornm. & Beauverd - Lebanon, Syria, Turkey, Iran
Onopordum carduelium Bolle - Canary Islands
Onopordum carduiforme Boiss. - Egypt, Palestine, Lebanon, Syria, Israel, Jordan
Onopordum carmanicum (Bornm.) Bornm. - Iran
Onopordum caulescens d'Urv. - Greece
Onopordum cinereum Grossh. - Caucasus, Turkey, Iran, Turkmenistan, Afghanistan
Onopordum corymbosum Willk. - France, Spain
Onopordum cynarocephalum Boiss. & Blanche - Palestine, Lebanon, Syria, Israel, Jordan
Onopordum cyrenaicum Maire & Weiller - Libya
Onopordum dissectum Murb. - Spain, Morocco
Onopordum dyris Maire - Morocco
Onopordum elongatum Lam.
Onopordum eriocephalum Rouy - France
Onopordum espinae Coss.
Onopordum heteracanthum C.A.Mey. - Caucasus, Lebanon, Turkey, Syria, Palestine, Iran, Afghanistan, Saudi Arabia
Onopordum horridum Viv. - Italy
Onopordum illyricum L. - Illyrian thistle, Illyrian cottonthistle - Mediterranean
Onopordum leptolepis DC. - from Palestine to Altay + Xinjiang
Onopordum macracanthum Schousb. - Spain, Portugal, Italy, Morocco, Algeria
Onopordum macrocanthum d'Urv.
Onopordum macrocephalum Eig - Palestine, Lebanon, Syria, Israel, Jordan
Onopordum mesatlanticum Emb. & Maire - Morocco
Onopordum micropterum Pau - Spain, Canary Islands
Onopordum minor L. - Iran
Onopordum myriacanthum Boiss. - Greece, Turkey, Bulgaria
Onopordum nervosum Boiss. - Moor's cottonthistle - Spain, Portugal
Onopordum parnassicum Boiss. & Heldr. - Greece, Turkey
Onopordum platylepis (Coss. ex Murb.) Murb. - Libya, Tunisia
Onopordum polycephalum Boiss. - Turkey
Onopordum prjachinii Tamamsch. - Uzbekistan, Kyrgyzstan, Tajikistan
Onopordum seravschanicum Tamamsch. - Uzbekistan, Kyrgyzstan, Tajikistan
Onopordum sibthorpianum Boiss. & Heldr. - Greece, Sicily, Malta, Turkey, North Macedonia, Saudi Arabia
Onopordum tauricum Willd. - Turkish thistle, Taurian thistle, Taurus cottonthistle, bull cottonthistle - southern + central Europe, Ukraine, Middle East
Onopordum turcicum Danin - Turkey
Onopordum wallianum Maire - Morocco
Natural hybrids
Onopordum × brevicaule (Onopordum acaulon × Onopordum acanthium )
Onopordum × erectum (Onopordum nervosum ssp. castellanum × Onopordum tauricum ssp. corymbosum )
Onopordum × macronervosum (Onopordum nervosum × Onopordum macrocanthum)
Onopordum × onubense (Onopordum dissectum × Onopordum macrocanthum)
Onopordum × spinosissimum (Onopordum illyricum × Onopordum acanthium)
Invasive problems
Some species of Onopordum have been introduced as ornamental plants in the temperate regions of North America and Australia, where they have become naturalised in the wild. In most of these countries, these thistles are considered noxious weeds, especially in Australia where a biological control program has been set up (using the Rosette Crown Weevil, Trichosirocalus briesei). In North America, there are also Trichosirocalus control programs, but they have proved detrimental to native thistles.
References
Briese, D.T., Lane, D., Hyde-Wyatt, B.H., Crocker, J., Diver, R.G. (1990). Distribution of thistles of the genus Onopordum in Australia. Plant Protection Quarterly 5: 23-27.
Asteraceae genera